Tractive-Force Distribution in Open Channels

Abstract: Tractive-force distribution in open channels are derived with the aid of simplifying assumptions that reduce the turbulent flow problem to the computer solution of laminar flow equations. Boundary drag and other effects, caused by restraint of the turbulent fluctuations at the wall and the free surface, are considered to originate two superimposed laminar velocity distributions on the same flow. Two laminar flow cases are solved; (1) The usual laminar open channel case, and (2) a closed channel, or pipe, having the same cross-sectional shape as the open channel. The two solutions are superimposed to obtain the final velocity distribution from which the tractive-force distribution is derived. The relative influence of the two solutions on the final velocity distribution is determined experimentally based on channel geometry and roughness. It is assumed that the relative tractive force distributions for these laminar-type flows are similar.